1. Field of the Invention
This invention pertains generally to resistance welding machines and particularly to those adapted to weld metal parts within a metal tube.
2. Description of the Prior Art
Tubes having welded metal baffles on the interior surface of the tubes are commonly used as heat exchange members in boilers, water heaters and in other heat exchange devices. Prior apparatus for welding such baffles within a tube is shown in the U.S. patent to Bock, U.S. Pat. No. 3,600,548. In the machine disclosed therein, the welding head is mounted on a rigid arm that can be extended into the tube. Flat steel baffles are fed down the length of the arm to a mechanism which engages a single baffle and places it in a transversely movable cross head. The cross head is driven by a piston under pressure to force one of the baffles against the tube inside wall, at which time a surge of current causes the baffle to be welded to the wall. The physical size of this mechanism and the space required to allow the transverse movement of the cross head limits the use of the mechanism to larger diameter tubes. The transversely moveable cross head has also been subject to erratic movement and, as might be expected, it is also subject to rapid wear because of the sliding action required.